Plagiarism is the ultimate form of academic dishonesty. It is trying to pass someone else's work and/or words off as your own.
Most students realize that they are not supposed to quote from another author's work without citing him/her. But a lot of students do not realize that paraphrasing another author without citing that author is also plagiarism.
Paraphrasing is when you take someone else's thoughts and restate them in your own words. In paraphrasing, although the words are your own, the ideas are someone else's. Therefore, if you do not cite the author you are paraphrasing, you are guilty of Plagiarism.
You need to be sure to include your own analysis because you should be actively contributing to the academic "conversation." However, scholarship is ultimately a communal activity.
When in doubt, cite your source. It is better to look unoriginal than to look dishonest.